If I intend to run an LED with a 5V source voltage and an LED forward voltage of 2V at 20ma it is my understanding that a 150 ohm resistor is suited.
I get this from using the formula
V = IR rearranged to
R = V/I.
R = 3/0.02
A 3V voltage difference at 20ma.
This works in practice as well, the LED is well lit and I get the forward voltage and current I expect when measured.
How exactly are these concepts related? It is my understanding that at at V voltage with R resistance, a maximum of I current will be allowed through. Is my understanding of these concepts over simplified or valid?